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Bacteriology > bact growth: physical and chemical requirements > Flashcards

bact growth: physical and chemical requirements Flashcards

1
Q

what is bacterial growth?

A

increase in the NUMBER of cells and not the size of cells

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2
Q

how do bacteria multiply?

A

binary fission (asexual)

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3
Q

what is generation time?

A

time required for one cell to become two cells

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4
Q

what are the two measurements of bacterial growth?

A

direct method

indirect method

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5
Q

what is the direct method of measuring bacterial growth?

A
  • microscopic counts

- viable counts

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6
Q

what is microscopic counts?

A

both live and dead cells are counted (total cell count)

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7
Q

what are viable counts?

A

only live cells are counted

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8
Q

what is serial dilution?

A

in viable counts: samples are diluted, generally 10-fold, to be counted

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9
Q

what are indirect methods of measuring bacterial growth?

A
  • measure turbidity in a spectrophotometer

- absorbance or optical density

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10
Q

what are the four phases of bacterial growth on the growth curve?

A

lag, log, stationary, death

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11
Q

what are the physical requirements of bacterial growth?

A

oxygen, CO2, temperature, pH, and osmotic pressure

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12
Q

what are the chemical requirements of bacterial growth?

A

nutrients

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13
Q

what are the 3 types of aerobes?

A

-obligate
-facultative
microaerophilic

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14
Q

what is the relationship to O2 and type of energy metabolism of obligate aerobes?

A
  • required

- aerobic respiration

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15
Q

what is the relationship to O2 and type of energy metabolism of facultative aerobes

A
  • O2 not required by better growth with O2

- aerobic respiration and fermentation

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16
Q

what is the relationship to O2 and type of energy metabolism of microaerophillic aerobes?

A
  • O2 required but at a lower concentration

- aerobic respiration

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17
Q

what is the relationship to O2 and type of energy metabolism of aerotolerant anaerobes?

A
  • O2 not required

- fermentation

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18
Q

what is the relationship to O2 and type of energy metabolism of obligate anaerobes?

A
  • O2 not required, its harmful

- fermentation

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19
Q

what are the toxic forms of oxygen

A
  • singlet oxygen
  • superoxide oxygen
  • peroxide anion
  • hydroxy radical
20
Q

how do toxic forms of oxygen inhibit or kill bacteria?

A

by disrupting nucleic acid and protein structures

21
Q

what 3 enzymes detox oxygen radicals?

A
  • catalase
  • peroxidase
  • superoxide dismutase
22
Q

what is required for biosynthesis?

A

carbon dioxide

23
Q

what bacteria thrives in temps 10 to 15 C?

A

psychrophiles

24
Q

what bacteria thrives in temps 30 to 37 C

A

mesophiles

25
Q

what bacteria thrives in temps >55 C

A

thermophiles

26
Q

what is the optimal physiological pH?

A

6.8-7.2

27
Q

are fungi bothered by pH?

A

no, they are acid tolerant

28
Q

what is the physiological ionic strength?

A

0.65% NaCl

29
Q

2 requirements for chemical growth

A

carbon and energy

30
Q

carbon required for chemical growth

A

CO2 and organic

31
Q

energy requirements for chemical growth

A

light or chemical

32
Q

pathogens have what chemical requirements for growth?

A

organic molecules for energy and carbon

33
Q

nutrient requirements: macronutrients

A

carbon, nitrogen (others like S, K, P, Na, Ca etc)

34
Q

nutrient requirements: micronutrients

A

Metals (Cu, Ze, Fe, Mn, Mo, etc)

35
Q

what metal plays a major role in respiration?

A

iron

36
Q

host Fe is tied up to what proteins?

A

transferrin and lactoferrin

37
Q

what are siderophores?

A
  • iron-binding agents produced by bacteria
  • enterobactins (E. coli and Salmonella)
  • bind to Fe and transport to cell
38
Q

what is culture medium?

A

nutrient solution required for growth

  • liquid (broth)
  • solid (agar)
39
Q

what is inoculum?

A

bacterial cells to the medium to initiate growth

40
Q

what is culture?

A

bacterial growth in a medium

41
Q

what is a defined medium?

A

exact chemical composition is known, pure chemicals are used

42
Q

what is a complex medium?

A

chemical composition is not know. has complex substances

43
Q

what is a general purpose medium?

A

allows growth of most bacteria

44
Q

what is a selective medium?

A

suppresses growth of unwanted bacteria and promotes growth of desired bacteria

45
Q

what is enrichment medium?

A

a liquid medium designed to increase growth of a desired bacteria

46
Q

what is differential medium?

A

differentiates two or more types of bacteria. -generally a solid medium

Bacteriology (17 decks)

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